1. Field of the Invention
The present invention relates to a backlight module and a method for coating a thermal conducting material on the backlight module, and more particularly, to a backlight module where the thermal conducting material is coated on specific areas of the back frame.
2. Description of the Prior Art
An advanced monitor with multiple functions is an important feature for use in current consumer electronic products. Liquid crystal displays (LCDs) which are colorful monitors with high resolution are widely used in various electronic products such as monitors for mobile phones, personal digital assistants (PDAs), digital cameras, laptop computers, and notebook computers.
A backlight module is one of the basic components of a liquid crystal display (LCD). Liquid crystals cannot emit light, so only through light sources provided by the backlight module can a desired image be shown. The operating principle of the backlight module is that light produced by backlight sources enters a light guide plate (LGP) and is guided to be a flat light source to ensure uniform brightness. Backlight sources used in the backlight module generally include cold cathode fluorescent lamps (CCFLs) and lighting emitting diodes (LEDs). Compared with traditional fluorescent tube lamps, LEDs have the characteristics of eco-friendliness, a small volume, a long product life, easy driving, low power consumption, and excellent seismic resistance. Owing to these merits, LEDs have gradually replaced traditional fluorescent tube lamps in recent years.
In a backlight module using LEDs as backlight sources, thermal energy produced by the LED backlight sources can be conducted outside of the backlight module through the back frame to dissipate heat. But the temperature is not uniform across the back frame during the process of heat dissipation; instead, the temperature differs from one area of the back frame to another area. Accordingly, stress is produced because of thermal expansion caused by the differences in temperature.
The stress has two defects. One is that optical properties of an optical film and an LGP are affected, causing the optical film and the LGP to produce birefringence and further causing mura (i.e., uneven color distribution) once images are shown on the LCD screen. The other is that an LGP and a back frame may be thus deformed, further affecting light transmission and illumination uniformity of the LGP.
Therefore, there is a need for the IT industry to design a backlight module capable of keeping temperatures uniform during the process of heat dissipation to avoid the problem occurring in the conventional technology.